Output power equalization of laser dual spectrum lines is a special requirement which is put on its laser source by two wavelength beat wave absolute distance interferometry.On the basis of analyzing the output signal of a two wavelength beat wave absolute distance interferometer

this paper proceeds from the realities of the aiming method of the beat wave interferometer

conducts an analytical investigations on the dependence of the aiming accuracy of the beat wave interferometer on laser dual line output power equilibrium

propose two new concepts-a basic aim blind area and a blind area expansion

and establishes an analytical expression between the blind area expanssion and the relative power difference of laser dual lines.The result provides an analytical tool for designing the laser stabilized servo loop of the instrument and improving its aiming accuracy.